PostgreSQL full text search yielding weird results - postgresql

Question

I have a schema like this (simplified):
CREATE TABLE users (
id SERIAL PRIMARY KEY,
name NOT NULL
);
CREATE INDEX users_idx
ON users
USING GIN (to_tsvector('finnish', name));
But I'm getting completely invalid results with my queries:
# select name from users where to_tsvector('finnish', name) ## to_tsquery('lemmin');
name
------
(0 rows)
# select name from users where to_tsvector('finnish', name) ## to_tsquery('lemmink');
name
--------------------
Riitta ja Lemminki
Riitta ja Lemminki
(2 rows)
# select name from users where name ilike 'lemmink%';
name
----------------------
Lemminkäinen Matilda
Lemminkäinen Matias
Lemminkäinen Kyösti
Lemminkäinen Tuomas
(4 rows)
Another example:
# select name from users where to_tsvector('finnish', name) ## to_tsquery('partu');
name
----------
Partuuna
(1 row)
# select name from users where to_tsvector('finnish', name) ## to_tsquery('partur');
name
------------------------
Parturi-Kampaamo Raija
Parturi-Kampaamo Siema
(2 rows)
I was expecting to get the bottom two results on both queries...
Using the following version:
psql (9.4.6, server 9.5.2)
WARNING: psql major version 9.4, server major version 9.5.
Some psql features might not work.

Answer 1

I don't speak Finnish, but it seems expected result. FTS looks for lexemes, not for parts of words, Eg, do is not a lexemme for dog, but dog is for dogs:
t=# select to_tsvector('english', 'Dogs eats bone') ## to_tsquery('do');
NOTICE: text-search query contains only stop words or doesn't contain lexemes, ignored
?column?
----------
f
(1 row)
t=# select to_tsvector('english', 'Dogs eats bone') ## to_tsquery('dog');
?column?
----------
t
(1 row)
So I believe in Parturi last i is optional ending - right?..
Update:
from https://en.wiktionary.org/wiki/parturi :
partur[i], partur[eita] => lexeme will be partur